Question

Calculate the heat change accompanying the transformation of C(graphite) to C(diamond). You are given:

$straight C left parenthesis graphite right parenthesis space plus space straight O subscript 2 left parenthesis straight g right parenthesis space rightwards arrow space space space space CO subscript 2 left parenthesis straight g right parenthesis semicolon space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 393.5 space kJ straight C left parenthesis diamond right parenthesis space plus space straight O subscript 2 left parenthesis straight g right parenthesis space space space rightwards arrow space space space CO subscript 2 left parenthesis straight g right parenthesis semicolon space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 395.4 space kJ$

Solution

The equation,
$straight C left parenthesis graphite right parenthesis space space space rightwards arrow space space space space straight C left parenthesis diamond right parenthesis space space space semicolon space space space increment subscript straight r straight H to the power of 0 space equals space ?$
Given that
$left parenthesis straight i right parenthesis straight C left parenthesis graphite right parenthesis space plus space straight O subscript 2 left parenthesis straight g right parenthesis space space space rightwards arrow space space space space CO subscript 2 left parenthesis straight g right parenthesis semicolon space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 393.5 space kJ left parenthesis ii right parenthesis space straight C left parenthesis diamond right parenthesis space plus space straight O subscript 2 left parenthesis straight g right parenthesis space space rightwards arrow CO subscript 2 left parenthesis straight g right parenthesis semicolon space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 395.4 space kJ$
Subtracting equation (ii) from equation (i), we have,
$straight C plus straight O subscript 2 left parenthesis straight g right parenthesis space minus space straight C space minus space straight O subscript 2 left parenthesis straight g right parenthesis space space space rightwards arrow space space space CO subscript 2 left parenthesis straight g right parenthesis space minus space CO subscript 2 left parenthesis straight g right parenthesis semicolon space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 393.5 space plus space 395.4 or space space straight C left parenthesis graphite right parenthesis space space rightwards arrow space space straight C left parenthesis diamond right parenthesis semicolon space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space minus 393.5 plus 395.4 or space space straight C left parenthesis graphite right parenthesis space rightwards arrow space space space space space straight C left parenthesis diamond right parenthesis space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment subscript straight r straight H to the power of 0 space equals space plus 1.9 space kJ space space space space space space space space space space space space space space space space$
i.e. 1.9 kJ of heat is absorbed in the process.

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Thermodynamics

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Give one difference between an isothermal and an adiabatic process.

For the process to occur under adiabatic conditions, the correct condition is

Define internal energy of a system

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